1. Field of the Invention
The present invention relates to an embryo quality evaluation assistance system that assists quality evaluation of an embryo, etc. The assistance system comprises an embryo observing apparatus having an image pickup unit for picking up an image of an embryo and a computer for transmitting/receiving data to/from the embryo observing apparatus.
2. Description of the Related Art
There is known a technique of culturing embryos of cattle, etc. in an incubator and making these embryos grow until they reach an implantable stage. In the case of in-vitro embryos of cattle, a skilled person takes out the embryos from an incubator on the seventh day from start of the culture and observes these embryos through a microscope to evaluate the final quality of the embryos.
FIG. 26 is a diagram showing quality codes of embryos of cattle. A skilled person observes embryos through a microscope to judge respective features (growth stage, degenerated site, morphology, zona pellucida). Then, the skilled person determines a quality code for each of embryos in accordance with an application. The degenerated site is a site at which cells are abnormal or become extinct.
FIG. 27 is a diagram showing the relationship between elapsed days after fertilization of a cow and growth stages. As shown in FIG. 27, the embryos are passed through cleavage embryos (one-cell embryo→2-cell embryo→4-cell embryo→8-cell embryo), and then become morulas after five to six days elapse from the pregnancy. Thereafter, in the process of compact morula→early blastocyst→blastocyst, raptures in which an embryo expands and contracts occur.
However, it is a great stress for embryos that the embryos are taken out from an incubator and observed. Therefore, there has been proposed a mechanism of evaluating the quality of embryos without taking out the embryos from the incubator (see Japanese Patent No. 3693907).
According to the above patent publication, an embryo is moved so as to be located at the center of the visual field of a microscope by operating a sample holder to measure the size of the embryo and also observe the morphology thereof. An oxygen consumption amount is measured on the basis of the measurement and observation results, thereby evaluating the quality of the embryo.
However, in the above patent, a person is required to operate the sample holder to hold an embryo every image pickup operation. Accordingly, images of an embryo cannot be picked up with time, and thus variation of growth stages cannot be observed.
Furthermore, as another problem, it is difficult to identify the boundary between the cells of a cleavage embryo on the basis of a pick-up image. For example, it is difficult to accurately extract the boundary between the cells by executing even edge enhancement processing. Accordingly, when cells are identified through image processing and quality of an embryo is evaluated on the basis of the feature amount of each cell, it would be impossible to evaluate quality of an embryo with high precision if the above problem is not solved.
Still furthermore, evaluation based on visual observation (check) induces dispersion among evaluators, and thus it is desired to evaluate on the basis of information obtained from only pickup images. Therefore, not only the size of the embryo, but also a lot of quantitative information is required.
At present, a research using information in the growth process such as an arrival time to respective growth stages, an occurrence frequency of raptures and a recovery time from raptures has been done in place of the conventional evaluation method (the method of performing observation and evaluation on the seventh day in the culture by the skilled person). Accordingly, it is very beneficial that information in the growth process as described above can be obtained from only pickup images.